Antenna array systems will be a ubiquitous component in forthcoming 5G (fifth generation) communication systems as a means of improving capacity at the presently used low GHz frequencies but more so to ensure sufficient coverage as the operating frequency extends to the mmW range. Antenna arrays typically consists of a regular structure of equi-spaced antenna elements.
Antenna arrays can be used to simultaneously transmit or receive multiple layers, e.g. through multiple beams in the special case of line-of-sight (LOS) communication or more generally through the concept of MU-MIMO (multi-user MIMO (multiple-input multiple-output)). During beam forming the antenna correlation properties are important such that highly correlated antennas may be combined coherently and thereby increasing the transmission efficiency. Typically, adjacent antennas present a higher correlation than distant antenna elements.
One key parameter when designing the 5G concept is energy efficiency. A base station may be equipped with a high number of antenna elements, even in the order of hundreds, and include a plurality of transceiver integrated circuits (ICs). In some use scenarios, all antenna elements and transceiver ICs might not be needed. Hence there is an opportunity to implement energy saving schemes by disabling, or inactivating, parts of the base station, sometimes even inactivating one or more complete transceiver IC.